In order to assess factors which might clinically modify shivering associated with extradural anesthesia, 84 parturients were randomly divided into 4 groups. Group I received extradural block with 0.5% bupivacaine at room temperature. Group II received plain 0.5% bupivacaine warmed to 38.5–39°C. Group III received room temperature 0.5% bupivacaine with added 1:200,000 epinephrine. Group IV received room temperature 0.5% bupivacaine with 50 jug of fentanyl. The injectate volume was 10 ml in all patients. Data collected included demographics, cardiorespiratory parameters, pain and anxiety levels, labor ward ambient temperature, presence or absence of shivering before blockade, post block development of analgesia, presence of shivering, patient temperature and cardiovascular parameters.